The presently disclosed subject matter relates to an optical sensor, and particularly to an optical sensor to be used in pulse oximetry for a neonate.
There is a pulse oximetry which is a technique for noninvasively measuring the arterial oxygen saturation which is one of indexes showing the condition of the subject. Pulse oximetry is performed by attaching an optical sensor including a light emitter and a light receiver, to, for example, the fingertip of the hand of the subject (for example, see Japanese Patent No. 3,896,408).
Since the fingertip of the hand of a neonate is very small, it is difficult to attach an optical sensor including a light emitter and a light receiver, to the fingertip. Therefore, a measurement is sometimes performed while an optical sensor is attached to the wrist or the palm. In the wrist, however, there are bones, and an abundant capillary bed does not exist unlike the fingertip, so that a measurement error is large. In the palm, by contrast, a gap tends to be formed between the skin surface and an optical sensor in accordance with a grasping motion due to the grasp reflex or the like, and therefore a measurement error is large.